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optimize: Refactor convert_to_jbig2

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This commit is contained in:
James R. Barlow
2018-10-02 23:42:12 -07:00
parent 4b27feca98
commit 75aad4cc79
1 changed files with 38 additions and 26 deletions
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src/ocrmypdf/optimize.py
+38 -26
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@@ -171,9 +171,43 @@ def extract_images(pike, root, log, options):
return jbig2_groups, jpegs, pngs
def _produce_jbig2_images(jbig2_groups, root, log, options):
def jbig2_group_future(executor, root, group, xref_exts):
prefix = 'group{:08d}'.format(group)
future = executor.submit(
jbig2enc.convert_group,
cwd=fspath(root),
infiles=(img_name(root, xref, ext) for xref, ext in xref_exts),
out_prefix=prefix
)
return future
def jbig2_single_future(executor, root, group, xref_exts):
prefix = 'group{:08d}'.format(group)
future = executor.submit(
jbig2enc.convert_single,
cwd=fspath(root),
infile=next((img_name(root, xref, ext) for xref, ext in xref_exts)),
outfile=root / (prefix + '.0000')
)
return future
if PAGE_GROUP_SIZE > 1:
jbig2_future = jbig2_group_future
else:
jbig2_future = jbig2_single_future
with concurrent.futures.ThreadPoolExecutor(
max_workers=options.jobs) as executor:
futures = (jbig2_future(executor, root, group, xref_exts)
for group, xref_exts in jbig2_groups.items())
for future in concurrent.futures.as_completed(futures):
proc = future.result()
log.debug(proc.stderr.decode())
def convert_to_jbig2(pike, jbig2_groups, root, log, options):
"""
Convert a group of JBIG2 images and insert into PDF.
"""Convert a group of JBIG2 images and insert into PDF.
We use a group because JBIG2 works best with a symbol dictionary that spans
multiple pages. When inserted back into the PDF, each JBIG2 must reference
@@ -183,31 +217,9 @@ def convert_to_jbig2(pike, jbig2_groups, root, log, options):
If too many pages shared the same dictionary JBIG2 encoding becomes more
expensive and less efficient.
"""
with concurrent.futures.ThreadPoolExecutor(
max_workers=options.jobs) as executor:
futures = []
for group, xref_exts in jbig2_groups.items():
prefix = 'group{:08d}'.format(group)
if PAGE_GROUP_SIZE > 1:
future = executor.submit(
jbig2enc.convert_group,
cwd=fspath(root),
infiles=(img_name(root, xref, ext) for xref, ext in xref_exts),
out_prefix=prefix
)
else:
future = executor.submit(
jbig2enc.convert_single,
cwd=fspath(root),
infile=next((img_name(root, xref, ext) for xref, ext in xref_exts)),
outfile=root / (prefix + '.0000')
)
futures.append(future)
for future in concurrent.futures.as_completed(futures):
proc = future.result()
log.debug(proc.stderr.decode())
_produce_jbig2_images(jbig2_groups, root, log, options)
for group, xref_exts in jbig2_groups.items():
prefix = 'group{:08d}'.format(group)